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Appendix B Detailed Information About Configurations
For information about selecting the best configuration for your system, see the PDF version of the eArray Director
Software: Installation and User's Guide located on the distribution CD ROM.
To determine the best configuration for your system, you need to answer some questions and make some decisions about
the type of configuration you need; what you can afford; and what components you have.
The following sections provide basic RAID and configuration information.
•
B.1 What is the purpose of your array? on page 213
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B.2 RAID Levels on page 214
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B.3 RAID Rules on page 216
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B.4 CAP Strategies Overview on page 216
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B.4.2 Configuring for Maximum Capacity on page 217
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B.4.3 Configuring for Maximum Availability on page 217
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B.5 RAID Levels and Availability on page 218
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B.6 Configuring for Maximum Performance on page 218
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B.6.1 Array Configuration Table: Overview on page 219
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B.6.2 Array Configuration Tables on page 219
B.1
What is the purpose of your array?
Think about this question before configuring the array. Is the array for increasing the capacity of your general-purpose
file and print server? Will the array support a database application running 24 hours a day? Will the array contain large
audio or video files to be played back on demand? Will the array serve as a repository for imaging systems?
Each of the above applications has a different access profile; the type and frequency of read and write activity performed
against the array over time. Identifying the data access profile will help you determine a strategy favoring capacity,
availability, or performance.
For example, so-called "video" servers typically write data (i.e., the video clip) infrequently, but play back the data very
often. The ratio of reading to writing in this type of an array is far different from a general-purpose file server, which is
handling small read and write operations all day long. In addition, the characteristics of the files themselves are very
different, video and image files are typically very large when compared to letters, memos and spreadsheet files.
Correct installation of the disk array and the controller requires a proper understanding of RAID technology and the
concepts described in this section.
RAID is an acronym for Redundant Array of Independent Disks. Disk array controllers implement several different
versions of the Berkeley RAID technology.
When System Drives are defined or created, an appropriate RAID level must be selected. This decision is based on the
following priorities:
•
Disk capacity utilized (number of drives)
•
Data redundancy (fault tolerance)
© 2003, Adaptec, Inc.
© 2003, 2002 LSI-Logic Corporation
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